Advanced organic-inorganic solid-chemical composition and methods for anaerobic bioremediation

ABSTRACT

The present invention discloses the formulation and use of an advanced solid-media chemical composition which includes both plant-derived and inorganic components which is designed and intended to enhance the removal of a broad range of recalcitrant organic and inorganic contaminants in the environment by provided an improved means of promoting the anaerobic, biologically mediated degradation, transformation, and/or detoxification of the contaminants which may be present in solid and liquid wastes, soils, sediments, and water bodies. The invention provides for improved means of (i) promoting the solid-phase extraction, absorption and adsorbtion of recalcitrant contaminants from contaminated media, (ii) creating, enhancing, and maintaining anaerobic and highly reducing conditions (i.e., negative Eh values), (iii) providing a sources of carbonaceous co-substrates, inorganic and organic anaerobic electron acceptors, and organic and inorganic nutrients to promote the growth of contaminant-degrading microorganisms, and (iv) providing sources of inoculum of naturally occurring microorganisms which act to promote the biodegradation of contaminants. Additional forms, means and methods for the production and use of the disclosed solid-chemical composition are also provided to provide additional advantages and to enhance other advantages provided by the composition and/or the components thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This invention can be used in conjunction with the liquid andsolid-chemical compositions for anaerobic bioremediation and the meansand methods for anaerobic bioremediation disclosed in the pendingapplication of Hince et al., Ser. No. 08/862,782, filed on May 23, 1997now U.S. Pat. No. 6,020,185, and other applications filed by Hince(filed Nov. 15, 1999), Hince and Singer (filed Nov. 15, 1999) and otherapplications soon to be filed by these inventors.

BACKGROUND

1. Field of the Invention

This invention discloses the formulation and use of an advancedsolid-media chemical composition designed and intended to enhance theremoval of halogenated organic contaminants and the oxidized forms ofinorganic contaminants from industrial wastes, soils, sediments,sludges, ground waters, surface waters, and the like. In particular,this invention provides an improved means of promoting the anaerobic,biologically mediated degradation, transformation and/or detoxificationof a broad range of recalcitrant and/or hydrophobic halogenated organicand inorganic contaminants in the environment, including, but notlimited to, organochlorine pesticides such as DDT and toxaphene; arsenicand/or arsenate-based pesticides; polychlorinated biphenyls (PCBs);dioxins; halogenated organic solvents such as perchloroethylene,trichloroethylene, trichloroethane, and freon; nitroaromatic compoundssuch as trinitrotoluene and other explosives and/or their byproducts;and toxic inorganic contaminants such as cyanide, hexavalent chromium,and the oxidized forms of other toxic heavy metals. This inventionprovides improved means for (i) promoting the solid-phase extraction ofrecalcitrant, hydrophobic contaminants from contaminated media andenhancing the bioavailability and biogeochemical reactivity of suchcontaminants, (ii) creating, enhancing and maintaining both stronglyanaerobic and highly reducing conditions favorable to thebiodegradation, dehalogenation, transformation and/or detoxification ofthese contaminants by naturally occurring microorganisms, (iii)providing a source of complex carbonaceous co-substrates, anaerobicelectron acceptors, and nutrients to promote the growth of thesecontaminant-degrading microorganisms, and (iv) providing sources ofinoculum of different types of naturally occurring microorganisms whichact to directly undertake or indirectly promote the biodegradation,dehalogenation, transformation, and/or detoxification of thesecontaminants. This invention specifically reveals an improvedcomposition and methods for its use for both solid organic and inorganicmaterials that are designed to promote one or more of the aforementionedprocesses, as well as for the combination of these solid organic andinorganic materials into the preferred embodiment of a singlecomposition which is both cost-effective and relatively simple to use inthe treatment of environmental contamination.

2. Description of the Prior Art

Soil and ground-water pollution caused by chemical contaminants releasedinto the environment is a well documented, worldwide problem. Suchchemical contamination is associated with many different types ofindustrial activities over the last two centuries. Common environmentalcontaminants include several different types and forms of petroleumhydrocarbons, halogenated organic compounds including solvents (e.g.,tetra- and trichloroethene, methylene chloride), pesticides (e.g., DDTand toxaphene), polychlorinated biphenyls (i.e., PCBs), nitroaromaticcompounds and heavy metals and other inorganic contaminants such ascyanides. The available toxicological data indicates that many of thesecontaminants, (in particular many of the halogenated organic compounds),are either carcinogenic or potentially carcinogenic to both man andanimals. In addition, the available environmental and ecological datahave shown that many of these contaminants tend to persist in theenvironment for long time periods and, consequently, they tend toaccumulate in the tissues of biological organisms up the food chain. Thelong-term stability and extremely slow degradation of many suchenvironmental contaminants presents a substantial, long-term hazard tohuman health and the environment throughout the industrialized world.

Many of the so-called conventional methods for the remediation orclean-up of chemically contaminated wastes, waters, soils and sedimentshave generally involved either the physical removal of the contaminatedmedia or the simple mass transfer of the contaminants from one media(e.g., soil) to another (e.g., air). In general, such physical-treatmenttechnologies do not involve the chemically and/or biologically mediatedbreakdown, transformation or detoxification of the contaminants. Two ofthe most common categories of physical environmental remediationtechnologies are the excavation of contaminated soils and the pumpingand subsequent treatment of contaminated ground water. The excavation ofcontaminated soils is often followed by their disposal in a landfill,which can pose a potential long-term risk to the environment. Manyground-water pump-and-treat processes involve the simple mass-transferor “stripping” of the contaminants from the water into the air. Anothercommon physical-treatment method involves the use of granular activatedcarbon (GAC) reactors to treat chemically contaminated waters. Whencontaminated water is passed through a GAC reactor, the contaminants arephysically adsorbed onto the carbon particles, thereby producing anothercontaminated media which requires subsequent disposal and/or treatment.Each of these physical-treatment technologies share the samedisadvantage-i.e., they do not reduce the actual amount or toxicity ofthe chemical contaminants, but rather they simply move the contaminationfrom one place to another or from one media to another.

Another well-known physical treatment process which involves the thermaltreatment or incineration of the contaminated materials can be aneffective albeit expensive means of breaking down the molecularstructure of the contaminants into non-hazardous products. For example,high-temperature incineration is known to be effective for the treatmentof materials containing pesticides and PCBs. Thermal-treatment methodsrequire the use of sophisticated and operation-and-maintenance-intensiveequipment, the costs of which are passed on to industry in the form ofexpensive unit costs for soil treatment. In addition, becausethermal-treatment processes are rarely, if ever, one-hundred-percenteffective in the destruction of the contaminants, they can produceatmospheric emissions of contaminants or the toxic by-products ofcontaminants. For example, the incomplete incineration of PCBs canproduce dioxins, which in turn are significantly more toxic than their“parent” PCB compounds.

A third category of environmental-remediation treatment technologies,bioremediation, involves the use of microorganisms to convert chemicalcompounds into innocuous or less harmful chemical compounds.Bioremediation technologies generally have lower costs associated withtheir use and implementation than do the competing physicaltechnologies. Bioremediation technologies are also more adaptable todifferent types of contamination problems and variations in fieldconditions than are physical-treatment technologies.

The most promising bioremediation technologies provide the additionalcapability of treating contaminated media in-situ, i.e., in placewithout the need for ground-water pumping or soil excavation. Currenttrends in bioremediation technology indicate that the most technicallyfeasible and commercially successful bioremediation technologies arethose which utilize indigenous or “native” contaminant-degradingbacteria (CDB), fungi and other microorganisms which are naturallypresent in the contaminated media. The presence of CDB in many differenttypes of environments has been extensively reported in the scientificliterature. There is an extensive body of prior art literature andpatents concerning various means of using both aerobic and anaerobic CDB(as well as engineered or cultured bacteria) to biodegrade organiccontaminants in water, soil and industrial wastes. For example, it hasbeen reported that native Alcaligenes spp., Pseudomonas spp., andEnterobacter spp. can degrade a number of pesticides and polychlorinatedbiphenyls (Nadeau et al., 1994, Applied and Environmental Microbiology;Aislabie et al., 1997, New Zealand Journal of Agricultural Research;Galli et al., 1992, Pseudomonas: Molecular Biology and Biotechnology).Given the significant advantages of using native microorganisms versusthe need to introduce cultured or engineered microorganisms, methodswhich involve the use of artificially introduced microorganisms (e.g.,U.S. Pat. No. 5,932,472) are declining in favor within both thescientific and engineering communities. Recent trends in the art andliterature acknowledge a growing understanding of the use of anaerobicbiological processes in the treatment of many different types ofcontaminants that are otherwise recalcitrant under aerobic conditions.In particular, trends in the art reflect a growing understanding of theneed and importance of achieving and maintaining anaerobic conditionsand other factors which favor the biologically mediated reduction,biodegradation, transformation and/or detoxification of recalcitrantorganic and inorganic contaminants in the environment.

The current understanding reflected by the art is that the recalcitrantnature of many halogenated organic contaminants, polynuclear aromatichydrocarbons (PAHs), other heavy (i.e., high-molecular weight)hydrocarbons, and the like is related to the hydrophobic nature andextremely low solubilities of the contaminants. Consequently, the“bioavailability” of these contaminants, i.e., their availability tobiological degradation processes mediated by microorganisms, isextremely limited under most environmental conditions. The prior artdescribes the use of chemical methods (e.g., Szejtli, et al., U.S. Pat.No. 5,425,881) and thermal methods (e.g., Rothmel, et al., U.S. Pat. No.5,567,324) to increase bioavailability. For a number of chemicallycomplex hydrophobic chlorinated organic compounds, such as pesticidesand PCBs, the prior art has suggested that the higher molecular weight(i.e., more chlorinated) compounds can not be practically biodegradedand thus bioremediation techniques have been all but abandoned withrespect to the treatment of such compounds in the environment. Forexample, through laboratory and pilot-scale experiments directed at theinvestigation of bioremediation processes on Hudson River sedimentscontaminated with PCBs, General Electric (GE) researchers determinedthat the PCBs associated with the sediments consisted of both a labile(i.e., biologically usable) fraction and a resistant (i.e., refractoryor relatively non-biologically usable) fraction (General ElectricCompany, 1992). The labile fraction was described by GE as thelower-molecular weight, less-chlorinated congeners that could be readilydesorbed from the sediments. GE described the resistant fraction as thehigher-molecular weight congeners that were adsorbed or otherwise boundto the natural organic matrix of the sediments thus greatly limitingtheir bioavailability to microorganisms. Inoculations with a purifiedPCB-degrading bacterial strain failed to improve the rate or extent ofPCB reduction in the GE experiments. In addition, the GE study did notinvestigate any means or methods to try to increase the bioavailabilityof the most recalcitrant PCB congeners. Furthermore, the GE researchfailed to address or disclose methods or means involving the use ofsolid or liquid compositions to create and control optimal anaerobicconditions and Eh-pH conditions favorable to the biodegradation of thePCBs.

Alternatively, and in contrast to the present invention, further studiesalong the lines of GE's prior work have all but given up on thebiodegradation of the resistant PCB congeners and have instead focusedon the potential reduction of the environmental risks posed by thesecongeners via the long-term biostabilization of these congeners in thesediments (Gan and Berthouex, 1994; Alcock et al., 1995). These studieshave further suggested that PCB biodegradation continues to occur slowlyover an extended time frame as specific PCB congeners becomebioavailable (Gan and Berthouex, 1994; Alcock et al., 1995).

Unlike the present invention, U.S. Pat. No. 5,789,649 to Batchelor etal. (E.I. du Pont de Nemours and Company) discloses a means for thedegradation of contaminants in soil consisting of adding both a“stabilizing agent” and a “reductive zero-valent metal and metalcatalyst.” In the process disclosed by Batchelor et al. (U.S. Pat. No.5,789,649), the contaminants are first stabilized within the solidmatrix using a “stabilizing agent,” such as that comprised of mixturesof bentonite clay and iron chloride. Batchelor et al. (U.S. Pat. No.5,789,649) further disclose the use of a “reductive zero-valent metaland metal catalyst” which provides for a “metallic couple” which leadsto the reductive dehalogenation of the halogenated organic compounds andthe consequent reduction of their concentration. Current understanding,however, reflects the need to extract, desorb, solubilize or otherwiseremove the contaminants from the solid or non-aqueous phases in order toincrease the bioavailability of the halogenated compounds tomicroorganisms to facilitate their biodegradation. Batchelor et al.(U.S. Pat. No. 5,789,649) do not disclose the chemical composition,methods or means of the present invention.

U.S. Pat. No. 5,266,213 to Gillham and peer-reviewed literature byGillham and O'Hannesin (Ground Water, 1994) disclose a remediationprocess limited to the treatment of ground water contaminated withchlorinated aliphatic compounds wherein the contaminated water is fedthrough a trench or tank containing a metal, such as iron fillings,under strict exclusion of oxygen (Eh values−100 to −200 mV). Thecontaminant breaks down under such reducing conditions into innocuousby-products. Based on the results of tests in which sodium azide wasadded to the columns, Gillham et al. concluded that the degradationprocess was abiotic in nature. Gillham (U.S. Pat. No. 5,266,213) opinedthat the degradation process involved the abiotic, electrochemicalreduction of the iron and the associated reductive dechlorination of theorganic compounds from the electrons produced by the reduction of theiron. However, the present invention discloses compositions and methodswhereby iron reduction (and the reduction of other metals) coupled tothe reductive-dehalogenation of organic contaminants is a biologicallymediated process. Therefore, Gillham (U.S. Pat. No. 5,266,213) andGillham and O'Hannesin (Ground Water, 1994) do not disclose the presentinvention.

Sayles et al. (Environmental Science and Technology, 1997) investigatedthe utility of using zero-valent iron (e.g., granular iron filings andthe like) to dechlorinate DDT and related compounds in an anaerobicaqueous environment. Sayles et al. also acknowledged the importance ofproviding for a large surface-area of reactive iron, such as that whichcould be facilitated by the use of a fine particulate or powdered formsof iron. Sayles et al. also investigated the use of a surfactant toincrease the availability of DDT to the “chemical” reactions catalyzedby the zero-valent iron. Like Gillham (U.S. Pat. No. 5,266,213) andGillham and O'Hannesin (Ground Water, 1994), Sayles et al do notdisclose the use of more than a single inorganic amendment (i.e., inaddition to the iron) to help optimize or control Eh-pH conditions. LikeGillham (U.S. Pat. No. 5,266,213) and Gillham and O'Hannesin (GroundWater, 1994), Sayles et al. also fail to acknowledge, investigate orotherwise disclose biologically mediated reductive-dehalogenation means,methods, or compositions. Therefore, Sayles et al. does not disclose thepresent invention.

U.S. Pat. No. 5,902,744 to Gray et al. (Stauffer Management Company)teaches the art of composting organic nutrients (e.g., manure, activatedsludge) and a bulking material (e.g., alfalfa) to decontaminate toxiccyclical chlorinated aromatic compounds. The method disclosed by Gray etal. also describes the use of cyclical and/or alternating aerobic andanaerobic treatment steps. Gray et al. does not discuss or disclose theart of using the plant material to increase the bioavailability orbiogeochemical reactivity of the contaminants or the use of these plantmaterials to help create or control anaerobic conditions. Gray et al.also disclose means by which moist air is moved through the compost andchemical reducing agents, such as sulphite and acetate, are added tomaintain anaerobic conditions. Unlike the present invention, Gray et al.does not teach or disclose the importance of legume-related orplant-fiber degrading organisms to bioremediation processes whichinvolve the addition of plant-material or means or methods of enhancingthe growth and activity of such organisms to optimize the degradation ofcontaminants in association with plant material. Gray et al. (U.S. Pat.No. 5,902,744) does not disclose the composition or methods of thepresent invention.

Unlike the present invention, U.S. Pat. No. 5,100,455 to Pinckard andGill, and U.S. Pat. Nos. 5,525,139 and 5,609,668 to Gill disclose themethod of achieving specific carbon-to-nitrogen ratios, i.e, within therange of 10:1 to 30:1, as provided for by composting plant material fromthe families Leguminosae (e.g., alfalfa) and Gossypium (e.g., cotton) ata rate of up to 20% by volume of the contaminated soil. These patentsfurther disclose methods and means for the composting of the plantmaterial and the prior inoculation of such compost with soil from thechemical spill or with the contaminant(s) of concern at an off-sitelocation by establishing compost windrows in order to establishpopulations of the indigenous, presumably contaminant-degradingbacteria. Furthermore, the methods and means described by this prior artare unclear as to whether the contaminated materials must be treated atan off-site location or whether the compost can be applied in-situ.These prior art patents also do not teach or disclose the importance oflegume-related or plant-fiber degrading microorganisms to bioremediationprocesses which involve the addition of plant-material or means ormethods of enhancing the growth and activity of such organisms tooptimize the degradation of contaminants in association with the plantmaterial. Accordingly, Pinckard and Gill (U.S. Pat. No. 5,100,455) andGill (U.S. Pat. Nos. 5,525,139 and 5,609,668) do not disclose thepresent invention.

Burge (J. Agr. Food Chem., 1971) and Guenzi and Beard (Science, 1967;Soil Sci. Soc. Amer., 1968) investigated the use of “ground alfalfa” or“alfalfa volatiles” obtained by the distillation of an alfalfa-waterslurry to enhance the anaerobic degradation of DDT from soil. Parr andSmith (Soil Science, 1976) teach a similar method for the degradation oftoxaphene. The results of each of these prior studies indicated that theprocesses of pesticide dechlorination were both biological and anaerobicin nature. These investigators hypothesized that the addition of theplant material provided energy which in turn increased the rates ofcontaminant conversion by the microorganisms. None of the prior artdescribed by Burge (J. Agr. Food Chem., 1971), Guenzi and Beard(Science, 1967; Soil Sci. Soc. Amer., 1968) and Parr and Smith (SoilScience, 1976) disclose the specific chemical compositions or methodsfor bioremediation of the present invention.

U.S. Pat. No. 5,609,667 to Dickerson (Product Services Co.) disclosesmeans and methods for bioremediation, limited to the bioremediation ofhydrocarbon-contaminated soils, which incorporate the use of a solidcomposition comprised primarily of cotton-lint derived cellulosematerial (and/or other by-products of cotton and cotton-seed processing)as well as ammonium sulfate. Dickerson (U.S. Pat. No. 5,609,667) was acontinuation-in-part of an abandoned patent application, Ser. No.08/219,843 filed Mar. 30, 1994. Dickerson (U.S. Pat. No. 5,609,667)specifically discloses the superior “wicking” action of his cotton-lintcomposition relative to other cellulose-based compositions andclay-mineral based compositions with respect to its ability to removepetroleum hydrocarbons from contaminated soils. Dickerson (U.S. Pat. No.5,609,667) does not disclose the importance of legume-related orplant-fiber degrading microorganisms to bioremediation processes whichinvolve the addition of fibrous plant materials or means or methods ofenhancing the growth and activity of such organisms to optimize thedegradation of contaminants which become incorporated into the plantmaterials. Dickerson (U.S. Pat. No. 5,609,667) does not disclose thecompositions or methods of the present invention.

U.S. Pat. Nos. 5,411,664 and 5,618,427 to Seech et al. (W. R. Grace)disclose practically identical methods for the respective biodegradationof halogenated aromatic compounds (U.S. Pat. No. 5,411,664) andnitroaromatic compounds (U.S. Pat. No. 5,618,427). Both patents disclosethe use of both fibrous organic matter and multi-valent metal particlesto the contaminated media. These patents discuss adding these amendmentsto soil, water or sediments and subsequently incubating these mediaunder anaerobic conditions conducive to the growth of the indigenouscontaminant-degrading microorganisms. Like Dickerson (U.S. Pat. No.5,609,667), the patents to Seech et al. disclose that the fibrous natureof the plant materials used is important to enable the organiccontaminant to become absorbed into the fibrous structure of the plantmaterial which enhances the extent of contaminant removal from theenvironmental media. Unlike the present invention, Seech et al. alsodisclose the use of multi-valent metals, (preferably iron or magnesium),in combination with the fibrous plant matter wherein the multi-valentmetals are specifically capable of being both oxidized and reduced backand forth under normal environmental conditions. Seech et al. do notdisclose the importance of legume-related or plant-fiber degradingmicroorganisms to bioremediation processes which involve the addition offibrous plant materials or means or methods of enhancing the growth andactivity of such organisms to optimize the degradation of contaminantswhich become incorporated into the plant materials. U.S. Pat. Nos.5,411,664 and 5,618,427 to Seech et al. do not disclose the chemicalcompositions or methods taught in the present invention.

U.S. Pat. No. 5,078,899 to Garrison (Idaho Research Foundation, Inc.)discloses a method of treating mine drainage water to remove ferrichydroxide, which is not the subject of the present invention. AlthoughGarrison (U.S. Pat. No. 5,078,899) does not disclose the presentinvention, the present invention provides for the beneficial use of thewastes produced by the oxidation of mine-drainage waters, e.g., ferricoxides, hydroxides, oxyhydroxides and the like, as a component of thechemical composition disclosed herein.

SUMMARY OF THE INVENTION

In accordance with the present invention there is provided novel andimproved solid-chemical composition and associated methods and means forthe use of said composition to promote the anaerobic, biologicallymediated, degradation, transformation, and/or detoxification ofrecalcitrant organic and inorganic environmental contaminants present insolid and liquid wastes, soils, sediments, and water into non-hazardousand/or less hazardous by-products, including mineral forms of nitrogenand carbon. The principles of this invention provide for the relativelyrapid and cost-effective anaerobic, biologically mediateddecontamination of halogenated solvents such as tetrachloroethene (PCE),trichloroethene (TCE), 1,1,1-trichloroethane (1,1,1-TCA), freon and thelike; other recalcitrant halogenated organic compounds such as DDT,toxaphene, PCBs, dioxins, and the like; arsenic-based pesticides;nitroaromatic compounds; recalcitrant hydrocarbon contaminants such asfree-phase hydrocarbon fuels (e.g., gasoline, fuel oil), polynucleararomatic hydrocarbons (PAHs), other heavy hydrocarbons and the like; andrecalcitrant inorganic contaminants such as cyanides, hexavalentchromium and the oxidized forms of other toxic metals and the like.

A further object of the invention is to present means by which toovercome the disadvantages associated with not only the traditionalmethods of remediation previously described, but also the limitations ofother more recent and/or technically advanced methods and means ofchemical-reduction based remediation and bioremediation described in theprior art. The present invention has the further advantage that it canbe used effectively either ex-situ or in-situ. A preferred embodiment ofthe present invention offers the further advantage of providing a meansof promoting the bioremediation of contaminated sediments in-situbeneath bodies of natural water such as oceans, lakes, rivers, streams,and the like, and man-made water bodies such as waste-treatment lagoonsand the like. The present invention also provides for significant costsavings relative to other means and methods for environmentalremediation, as it can reduce or eliminate the need for excavation,pumpage, transportation, and/or off-site treatment of contaminatedwastes, soil, or water.

The present invention is based upon discoveries from recent and ongoingexperiments that several interrelated conditions must be achieved andmaintained within the matrix of the contaminated media to enable theeffective biodegradation of recalcitrant organic contaminants in theenvironment. Accordingly, the purpose of the present invention is toprovide a solid-chemical composition and methods and means for its usewhich serve to: (1) physically extract, absorb and adsorb hydrophobiccontaminants from contaminated wastes and environmental media, therebyincreasing the bioavailability and/or biogeochemical reactivity of thecontaminants; (2) create and maintain strongly anaerobic conditions byfacilitating the biologically mediated removal of the available oxygenfrom the media; (3) create and maintain optimal Eh-pH conditionsincluding strongly negative Eh conditions (Eh values ≦−200 millivolts)and near neutral to slightly acidic pH conditions (6≦pH ≦8) which favoranaerobic, biologically mediated chemical-reduction reactions, e.g., thereductive dehalogenation of halogenated organic contaminants; and (4)provide means for maintaining conditions (1)-(3) for sufficiently longperiods of time to enable the biologically mediated degradation,transformation, and/or detoxification reactions to proceed to the extentthat the concentrations and/or toxicity of the contaminants are reducedto acceptable levels.

The discoveries disclosed herein indicate and/or strongly suggest thatsuch contaminants can be effectively degraded, transformed and/ordetoxified by indigenous, contaminant-degrading bacteria when thesolid-chemical composition disclosed herein are applied to thecontaminated media and the media are subsequently maintained underconditions favorable to the anaerobic microorganisms and thebiogeochemical reactions mediated by these organisms, i.e., the mediaare maintained at near-saturation conditions with water. Through anumber of experiments conducted by the inventors, it has been furtherdiscovered that the organic solid-chemical composition disclosed hereinare capable of supporting the growth of indigenous bacterial populationswhich include both legume-related microorganisms such as Rhizobium spp.and Bradyrhizobium spp. and the like and fiber-degrading (i.e., lignin-and cellulose-degrading) bacteria such as Fibrobacter spp. For purposesof explanation and not limitation, it is believed that theaforementioned legume-related and fiber-degrading microorganisms greatlyenhance the anaerobic biodegradation, transformation, and/ordetoxification of recalcitrant contaminants either directly and/or bybreaking down the cellulose-containing materials to which thecontaminants which have become adhered to and/or impregnated within,thereby greatly increasing the bioavailability of the contaminants to abroad spectrum of other microorganisms.

In addition, the solid-chemical composition of the present inventiondisclosed herein can also provide for the creation and long-termmaintenance of a highly anaerobic and reducing environment, i.e., anoxicconditions coupled with strongly negative Eh values, which are requiredto promote the biodegradation, transformation, and/or detoxification ofcontaminants via biologically mediated chemical-reduction processes,e.g., reductive dehalogenation. The disclosed solid-chemical compositionprovides various forms of electrons, organic and inorganic electronacceptors and nutrients, organic and inorganic substrates formicroorganisms as well as optional inorganic nutrient forms of nitrogenand phosphorus and optional chelating and acidifying agents. These andother objects and advantages of the present invention will becomeapparent to those skilled in the art following the detailed descriptionof the invention which reveals the novel combination of solid chemicalcompositions described herein, and more particularly as defined by theappended claims.

BRIEF DESCRIPTION OF THE FIGURES

Embodiments of the present invention will now be described more fullywith reference to the following drawings in which;

FIG. 1 illustrates the effectiveness of several different embodiments ofthe disclosed chemical composition of the present invention with respectto control of redox conditions (Eh).

FIG. 2 shows the effect of several different embodiments of thedisclosed chemical composition of the present invention on DDTbiodegradation rates.

FIG. 3 shows the effect of several different embodiments of thedisclosed chemical composition on toxaphene biodegradation rates.

DETAILED DESCRIPTION OF THE INVENTION

The present invention disclosed herein provides a unique solid-chemicalcomposition for the bioremediation of wastes and environmental mediacontaminated with recalcitrant organic and inorganic contaminants. Inthe practice of the present invention, the disclosed solid-chemicalcomposition would first be prepared by mixing the components togetherand/or then manufacturing the composition in the form or pellets,tablets, capsules or the like prior to use at a contaminated site. Next,the disclosed solid-chemical composition is applied to, and ideally,mixed into the contaminated media (e.g., sludges, solid and/or liquidwastes, and the like), contaminated soil, sediment, or water, and thelike, to promote the anaerobic biodegradation, transformation, ordetoxification of the contaminants within said media.

The use as intended of the disclosed solid-chemical composition providesfor a combination of means, mechanisms, processes, factors, andcapabilities which enhance the anaerobic biodegradation, transformation,and/or detoxification of recalcitrant environmental contaminantsincluding:

(1) the plant-derived components in the disclosed solid-chemicalcomposition promote the physical and biogeochemical extraction,absorbtion and adsorbtion of the hydrophobic substances from thecontaminated media, thereby greatly increasing the bioavailability andbiogeochemical reactivity of the contaminants to a broad spectrum ofcontaminant-degrading microorganisms. These plant-derived materials alsopromote anaerobic and reducing conditions and provide sources of organicsubstrates, electron acceptors and nutrients for anaerobicmicroorganisms;

(2) The chemical composition disclosed herein provides combined sourcesof organic inoculum and substrates for soil, legume-related, andplant-fiber degrading microorganisms such as Pseudomonas spp., Rhizobiumspp., Bradyrhizobium spp., Fibrobacter spp., Clostridium spp., and thelike. For purposes of explanation and not limitation, it is believedthat the aforementioned legume-related and fiber-degradingmicroorganisms greatly enhance the anaerobic biodegradation,transformation, and/or detoxification of recalcitrant contaminantseither directly and/or by breaking down the plant-fiber materials whichin turn make the contaminants which have become adhered to and/orimpregnated therein available to a broad spectrum of anaerobicmicroorganisms. This latter advantage of the present inventionrepresents a major and extremely important advancement in the art.Hence, the solid-chemical composition disclosed herein provides uniqueadvantages which greatly enhance the speed and effectiveness of theanaerobic, biologically mediated biodegradation, transformation and/ordetoxification of recalcitrant contaminants.

(3) The organic materials derived from nitrogen-fixing plants includedin the solid-chemical composition disclosed herein provide a combinationof carbonaceous co-substrates, nitrogen-based electron acceptors such asnitrates and nitrites, complex nutrient forms of nitrogen such asamines, proteins and enzymes, and complex nutrient forms of phosphorussuch as phospholipids and fatty acids for anaerobic soil, legume-relatedand fiber-degrading microorganisms as well as for other anaerobicmicroorganisms capable of denitrification processes. Hence, the use ofthese nitrogen-fixing and/or leguminous plant materials as disclosed inthe present invention provides for ideal growth conditions of saidmicroorganisms. In addition, the nitrogenous electron acceptors andnutrients provided by these materials provide a means by which topromote the anaerobic biodegradation of the other organic components ofthe disclosed chemical composition, as well as the contaminantsincorporated therein, by organisms capable of denitrification,metal-reduction and other anaerobic respiration processes.

(4) The solid-chemical composition disclosed herein provides multipleand complimentary sources of inorganic electron acceptors formetal-reducing bacteria such as Geobacter spp., Geovibrio spp.,Pelobacter spp., Shewanella spp., Pseudomonas spp., Achromobacter spp.,Aeromonas spp., Bacillus spp., Enterobacter spp., Desulfuromonas spp.,Desulfovibrio spp., Micrococcus spp. and other metal-reducingmicroorganisms in the forms of both iron and manganese metallicmaterials, iron (III) and manganese (IV) containing minerals andbiogeochemically produced ferric oxides, hydroxides and oxyhydroxides.

(5) The solid-chemical composition disclosed herein provides multipleand complimentary sources of electrons which act to create and maintainreducing conditions (Eh values ≦−200 millivolts) within the matrix ofthe contaminated media, which in turn helps to catalyze anaerobic,biologically mediated chemical-reduction reactions which promote thebiodegradation, transformation and/or detoxification of recalcitrantcontaminants.

(6) The solid-chemical composition disclosed herein also includes theuse of special types and proportions of inorganic, manganese-containingmetals and/or mineral particles which serve as oxidative catalysts forthe selective and/or site-specific biogeochemical and/or electrochemicalformation, precipitation and/or deposition of metallic oxides,oxyhydroxides, sulfides, carbonates, and the like which would otherwisetend to precipitate onto the surfaces of the inorganic electron-acceptoramendments under the typical Eh-pH conditions created by the use of thesolid-chemical compositions disclosed herein. This latter advantage ofthe present invention represents a major and extremely importantadvancement in the art, as the metallic manganese and/or manganese (IV)mineral particles provide a means of preserving the availability of theiron-containing components of the composition such that highly reducingand relatively stable low-Eh conditions are maintained for long periodsof time relative to other means and methods disclosed in the prior art.Hence, the inorganic components of the solid-chemical compositiondisclosed herein provide unique advantages which greatly enhance thespeed and effectiveness of the anaerobic, biologically mediatedreductive dehalogenation of recalcitrant organic contaminants and thebiologically mediated reduction of inorganic contaminants.

(7) In addition to the foregoing, and for purposes of explanation andnot limitation, the biogeochemically produced (i.e., ‘biogenic’) ferricoxides, hydroxides, oxyhydroxides and the like which may be included inthe solid-chemical composition disclosed herein are believed to providea unique and important source of inoculum for metal-reducing bacteriasuch as Geobacter spp., Thiobacillus spp. and the like. Trends in therecent literature indicate or otherwise suggest the such metal-reducingmicroorganisms play and important role in the “natural” biodegradation,transformation, and/or detoxification of many contaminants in theenvironment. Hence, inclusion of the biogeochemically produced ferricoxides, hydroxides, and oxyhydroxides in the present invention a uniqueand improved means of enhancing the activity of such microorganisms.

Based on the foregoing and in accordance with the present invention,there are provided means for the enhanced anaerobic microbialdegradation, transformation and/or detoxification of recalcitrantorganic and inorganic chemical contaminants in wastes, soils, sediments,and comprising the formulation, processing and use of a uniquesolid-chemical composition. The solid-chemical composition of thepresent invention includes both organic and inorganic components.

In the preferred embodiment of the present invention, the firstplant-derived component (a) of the disclosed chemical compositionconstitutes from 10% to 95% of the total composition by weight and iscomprised of the dehydrated, dried, freeze-dried and/or industriallyprocessed forms of nitrogen-fixing plant materials selected from theplant families Leguminosae and Phaeophyta and/or (ii) agriculturallycultivated nitrogen-fixing, leguminous plant materials whereby saidplant materials are selected from the plant family Leguminosae. In thepreferred embodiment of the present invention in which leguminousmaterials are used in the disclosed composition, such materials wouldpreferably be selected from the group comprising Lespedeza spp.,Medicago ssp. (e.g., alfalfa), Vicia spp. (e.g., vetch), Glycine spp.(e.g., soy), Lathyrus spp. (e.g., indian vetch), Trifolium spp. (e.g.,clovers) and the like. In the preferred embodiment of the presentinvention in which materials from the plant family Phaeophyta are usedin the composition, such materials would preferably be selected from thegroup comprising Sargassum spp. In the preferred embodiment of thepresent invention, the dehydrated, dried, freeze-dried and/orindustrially or agriculturally processed forms of the nitrogen-fixingplant materials of component (a) are further selected from the groupcomprising powders, dusts, flours, pellets, meals, mids, husks, hulls,hays, straws and other commercially available forms of these materials.

In the preferred embodiment of the present invention, inorganiccomponent (b) of the chemical composition constitutes from 1% to 50% ofthe total composition by weight and is selected from the group comprisedof the fine granular and/or powdered forms of porous iron or steel,e.g., the “sponge” iron product Ancor Image 100 manufactured byHoeganaese and/or the like. Component (b) serves as the primaryinorganic source of electrons and inorganic, low-Eh electron acceptors,e.g., ferric iron, for iron-reducing bacteria including but not limitedto Geobacter spp., Geovibrio spp., Pelobacter spp., Shewanella spp.,Pseudomonas spp., Achromobacter spp., Aeromonas spp., Bacillus spp.,Enterobacter spp., Desulfuromonas spp., Desulfovibrio spp., Micrococcusspp. and other microorganisms capable of iron-reduction. Component (b)also serves as an inorganic substrate for said anaerobic, metal-reducingmicroorganisms. The aforementioned “sponge” form of fine-granular ironor steel is the preferred embodiment of component (b) because of itshigh surface area and porosity relative to its particle size.

In the preferred embodiment of the present invention, inorganiccomponent (c) of the chemical composition constitutes from 0.01% to37.5% of the total composition by weight and is selected from the groupcomprising the fine granular and/or powdered forms of metallic manganeseand/or manganese(IV)containing minerals such as pyrolusite, psilomelane,and the like. In addition, it is critical that the proportion ofcomponent (c) relative to component (b) is such that their weight ratiois in the range of 0.01-0.75. The principle function of component (c) isthat it serves as an oxidative catalyst for the selective and/orsite-specific biogeochemical and/or electrochemical formation,precipitation and/or deposition of metallic oxides, oxyhydroxides,sulfides, carbonates and the like. An additional function of component(c) of the composition is that it serves as an additional source ofelectrons and anaerobic-electron acceptor forms of manganese (IV) formanganese-reducing and other metal-reducing microorganisms capable ofmanganese-reduction. Component (c) further serves as an additionalinorganic substrate for anaerobic, metal-reducing microorganisms.

In the preferred embodiment of the present invention, anotherplant-derived component (d) of the chemical composition may constitutefrom 1% to 89% of the total composition by weight. In the preferredembodiment of the present invention, component (d) of the compositionwould be comprised of industrially processed or agriculturallycultivated plant materials selected from the families Gossypium (e.g.,cotton) and Cannabacea (e.g., hops and hemp). The general advantagesprovided for by the use of plant materials selected from the familiesGossypium and Cannabacea is that the physical-extraction of hydrophobiccontaminants is enhanced by the fibrous microstructure of such materialsas well as by the naturally occurring oils, resins and other hydrophobicsubstances present therein. A further distinction of the preferredembodiment of the present invention would include the beneficial use ofhighly absorbent cotton-containing waste materials such as cotton lint,cotton-mill processing ‘dust,’ and the like. A distinction of thepreferred embodiment of the present invention which includes the use ofplant materials selected from the family Cannabacea (e.g., hops andhemp) is that in addition to the fibrous nature of such materials, theycontain abundant amounts of relatively insoluble oils, resins and otherhydrophobic substances which should enhance the ability of thesematerials to physically and/or biogeochemically extract hydrophobiccontaminants from contaminated media. Additional advantages of the useof hemp materials in the present invention are the relatively low costsand environmental impacts associated with the production of these plantmaterials, relative to other agricultural products.

In the preferred embodiment of the present invention, another inorganiccomponent (e) of the disclosed chemical composition may constitute from0.1% to 40% of the total composition by weight and is selected from thegroup comprising sodium nitrate, sodium-potassium nitrate, potassiumnitrate and/or ferric nitrate and various manganese nitrates. Component(e) provides both a source of electron acceptors for denitrifyingbacteria and other anaerobic microorganisms capable of denitrificationprocesses and an ammonium-free source of nitrates as the sole inorganicform of nutrient nitrogen in the disclosed composition. In theembodiment of the present invention in which component (e) includesferric nitrate and manganese nitrates, component (e) would also provideelectron acceptor and nutrient forms of iron and manganese.

In the preferred embodiment of the present invention, another inorganiccomponent (f) of the disclosed composition may constitute from 0.02% to20% of the total composition by weight and is selected from the groupcomprising ringed metaphosphates and/or linear polyphosphates. Component(f) of the disclosed composition provides a source of complex,hydrolyzable phosphates as nutrients for anaerobic microorganisms. Theprovision of complex metaphosphates and/or polyphosphates providesnutrient phosphorus in forms which are relatively nonreactivegeochemically and hence more effectively and efficiently utilized bymicroorganisms. In addition, the complex phosphates in component (f)also serve as surfactants which enhance the biogeochemical reactivityand bioavailability of organic contaminants.

In the preferred embodiment of the present invention, component (g) thedisclosed solid-chemical composition may constitute from 0.01% to 5% ofthe total composition by weight and is selected from one or more of thegroup comprising citric acid, humic acid, fulvic acid, sodium citrateand EDTA. Component (g) of the disclosed composition provides a sourceof both chelating agents and acidifying agents which help promoteanaerobic, biologically mediated metal-reduction processes and otherbiogeochemical processes which are catalyzed by metals.

In the preferred embodiment of the present invention, citric acid isused as some or all of component (g) given that it is not only aneffective chelating agent and pH-reducing (i.e., acidifying) agent, butit is a weak organic acid which can help promote microbial processes.The use of humic and/or fulvic acids in component (g) provides similarand complimentary benefits to the described for the use of citric acid.

In the preferred embodiment of the present invention, component (h) ofthe disclosed chemical composition may constitute from 0.001% to 15% ofthe composition by weight and is comprised of one or morebiogeochemically produced ferric oxides, hydroxides and oxyhydroxides,such as those associated with acid-mine drainage and/or the treatmentby-products thereof. A further distinction of the aforementionedpreferred embodiment of the present invention is that such materialswould be of the type referred to as “yellow boy” and related materialswhich are products or by-products of mine drainage wastes and/or thetreatment thereof. For purposes of clarification and not limitation,results of the novel research associated with the present inventionsuggests that in addition to providing another source of electrons andferric-iron electron acceptors for metal-reducing bacteria, suchbiogeochemically produced ferric-iron containing materials also serve asinoculum for metal-reducing and oxidizing bacteria such as Geobacterspp., Thiobacillus spp., and the like. Component (h) is also believed toserve as an inorganic substrate for these metal-reducing andmetal-oxidizing microorganisms.

In the preferred embodiment of the present invention, component (i) ofthe disclosed chemical composition may constitute from 0.001% to 1% ofthe total composition by weight and is comprised of the dehydratedand/or freeze-dried forms of inoculum selected from one or more of thegroup comprising soil microorganisms (e.g., Pseudomonas spp.),legume-related microorganisms (e.g., Rhizobium spp., Bradyrhizobiumspp.), plant-fiber degrading (i.e., lignin-and cellulose-degrading)microorganisms (e.g., Fibrobacter spp., Clostridium spp., and variousspecies of fungi) and metal-reducing microorganisms (e.g., Geobacterspp.). In the preferred embodiment of the present invention, particularemphasis is placed on the use of inoculum for plant-fiber degradingmicroorganisms such as the anaerobic bacteria Fibrobacter spp.,Clostridium spp., and the like and/or plant-fiber degrading species offungi. Component (i) of the disclosed composition provides the advantageof ensuring for an adequate population of the important types ofmicroorganisms in relatively challenging, difficult or otherwise unusualremediation applications of the present invention such as thebioremediation of industrial or hazardous wastes, waste lagoons, naturalbodies of water (e.g., oceans, rivers, lakes, streams, and the like), ordeep sediments or rock formations where such microorganisms may not besufficiently abundant.

In the preferred embodiment of the present invention, an additionalplant-derived component (j) may constitute from 0.5% to 30% of the totalchemical composition by weight and is comprised of industriallyprocessed or agriculturally cultivated plant materials from the familiesTriticum and Aegilops (e.g., wheat, oats, and the like). In thepreferred embodiment of the present invention, component (j) of thedisclosed composition would include the fine particulate, dehydrated,dried or freeze-dried forms of agriculturally produced materials orwastes which contain wheat, oats, and the like, e.g., pellets, powders,flours, dusts, meals, mids, husks, hulls, straws or hays. Plant-derivedcomponent (i) of the disclosed composition not only provides anadditional capacity to physically extract, absorb or adsorb hydrophobiccontaminants, but provides an additional and complimentary source oforganic nutrients and carbonaceous co-substrates including complexsugars, starches, cellulose and lignin. Hence, component (j) of thedisclosed composition is believed to enhance the effectiveness of thedisclosed composition.

For purposes of explanation and not limitation, it is believed that theplant-derived materials included within the solid-chemical compositiondisclosed herein have the capacity to physically and/or biogeochemicallyextract, absorb and adsorb hydrophobic organic contaminants fromcontaminated media. In addition, these plant-derived components of thecomposition provide sources of organic co-substrates, electron donors,electron acceptors, nutrient forms of nitrogen and phosphorus andproteins and enzymes for promoting the anaerobic bioremediation ofcontaminants. In addition, these plant materials serve as both asubstrate for soil and/or legume-related bacteria such as Pseudomonasspp., Rhizobium spp., Bradyrhizobium spp., and the like, and plant-fiberdegrading (e.g., lignin and cellulose-degrading) bacteria such asFibrobacter spp., Clostridium spp., plant-fiber degrading fungi and thelike. It is further believed the complex enzymatic capabilities of thefiber-degrading microorganisms may enable these microorganisms to eitherdegrade the contaminants directly or as a co-metabolic function of thedegradation of the plant-derived materials included in the chemicalcomposition. Hence, after the contaminants are absorbed within the plantmaterial, the subsequent activity of fiber-degrading microorganisms suchas Fibrobacter spp., Clostridium spp., and plant-fiber degrading fungigreatly enhances the bioavailability and biogeochemical reactivity ofthe contaminants absorbed within or adhered to the contaminants withrespect to a broad range of other anaerobic, contaminant-degradingmicroorganisms.

For purposes of explanation and not limitation, the benefits of the useof nitrogen-fixing plant materials in the disclosed composition, such asthe aforementioned leguminous materials, includes the ability of suchmaterials to promote the growth and activity of anaerobicfiber-degrading bacteria, soil and/or legume-related bacteria and manyother types of anaerobic microorganisms which are specifically capableof denitrification-processes which utilize the nitrogenous electronacceptors and nutrients present in these materials. In addition, byproviding such nitrogen-fixing plant materials in the amounts whichcomprise at least 20% by weight of the total amount of plant materialsprovided by components (a), (d) and (j), these materials provide“excess” amounts of electron acceptors, and nutrient forms of nitrogenand phosphorus which promote the biodegradation of the otherplant-derived components of the composition as well as the contaminantsincorporated therein. Hence, the composition disclosed herein in whichthe first component of nitrogen-fixing plant materials are combined withthe additional plant materials and other components of the compositionprovide for significant advantages in the promotion of the anaerobicbioremediation of recalcitrant environmental contaminants versus othercompositions, methods and means for bioremediation disclosed in theprior art.

In the preferred embodiment of the present invention, the plantmaterials provided in components (a), (d) or (j) can either be appliedto contaminated media directly in the form of the fine-particulateand/or industrially processed forms of pellets, meals, mids, husks,hulls, hays, or straws or they can be agriculturally cultivated in-situby direct plantings of seeds or plants in the contaminated soils. Inaddition to applications in which the plant-derived components (a), (d)and (f) are applied together with the other components of the disclosedcomposition, the plant-derived components can alternatively be appliedto the contaminated media before or after the application of the othercomponents of the chemical composition. In the forms of the presentinvention whereby the plant-derived materials of components (a), (d) and(j) are agriculturally cultivated in-situ, such plants could berepeatedly cut and mulched to both increase the in-situ yield (i.e.,amount) of these plant materials and to decrease the particle size ofthese materials in order to enhance their incorporation into thecontaminated soils. A further aspect of the preferred embodiment of thepresent invention involving the agricultural cultivation of these plantmaterials would involve the overwintering of the plant materials whichis believed to enhance the physical and biogeochemical extraction of thehydrophobic contaminants and their biodegradation via the decay of theplant materials in-situ during the dormant, i.e, winter season. Forpurposes of explanation and not limitation, the aforementioned“overwintering” of the plant materials at sites in which freezingconditions are experienced over the course of a year is believed togreatly enhance the aforementioned advantages of the preferredembodiment of the present invention by freeze-drying and/orfreeze-fracturing of these materials, which consequently helps todistribute the plant materials throughout the soil matrix and enhancesthe ability of these materials to physically and/or biogeochemicallyextract and/or hydrophobic contaminants. Furthermore, the overwinteringprocess promotes the biodegradation/decomposition of the plantmaterials, which in turn promotes the anaerobic bioremediation ofcontaminants by providing a source of co-substrates, electron donors andacceptors, nutrients and the like to many different types ofmicroorganisms within the soil matrix.

The disclosed solid-chemical composition of the present invention alsoprovides multiple sources of inorganic electron acceptors for anaerobic,metal-reducing bacteria such as Geobacter spp., Geovibrio spp.,Pelobacter spp., Shewanella spp., Pseudomonas spp., Achromobacter spp.,Aeromonas spp., Bacillus spp., Enterobacter spp., Desulfuromonas spp.,Desulfovibrio spp., Micrococcus spp. and other microorganisms capable ofiron reduction, manganese reduction and the reduction of other metals.Based on information found in the recent literature and the researchconducted by the inventors, it is believed that the aforementionedmetal-reducing microorganisms play an important if not preeminent rolein the anaerobic, biologically mediated degradation, transformationand/or detoxification of recalcitrant contaminants in the environment.

A specific advantage provided for by the unique formulation of thesolid-chemical composition disclosed herein is that it serves to create,enhance and maintain highly reducing (i.e., Eh ≦−200 millivolts)conditions within the matrix of contaminated media to which it isapplied. Specific means for the maintenance of the highly reducingconditions is provided for by the use of the inorganic component (c),i.e., fine particles of metallic manganese and/or minerals containingmanganese (IV), which serve to catalyze the selective and/orsite-specific biogeochemical and/or electrochemical formation,precipitation and/or deposition of metallic oxides, oxyhydroxides,sulfides, carbonates, and the like. The said use as intended ofcomponent (c) is one of the most important advantages of the presentinvention over what has previously been disclosed in the prior art. Inparticular, the use as intended of component (c) causes inorganicminerals such as metallic oxides, oxyhydroxides, sulfides, carbonates,and the like to form at or near the surfaces of the metallic manganeseand/or minerals containing manganese (IV) instead of at or near thesurfaces of the first inorganic amendment (i.e., sponge-iron particles).The biogeochemical conditions which typically arise from the use of thedisclosed chemical composition are such that metallic oxides,oxyhydroxides, sulfides, carbonates, and the like would normally tend toform at or near the surfaces of the sponge-iron particles. However, theuse of component (c) acts to control and direct the location of thedeposition of the metallic oxides, oxyhydroxides, sulfides, carbonates,and the like away from the surfaces of the sponge-iron particles,leaving the surfaces of the sponge-iron particles available toiron-reducing and other metal-reducing microorganisms therebymaintaining relatively stable, low-Eh conditions (e.g., Eh values ≦−200millivolts) within the contaminated media being treated. Recentexperimental data concerning the present invention indicates that it isessential that the disclosed amounts and proportions of component (c) tocomponent (b) be strictly maintained. Recent experimental data has shownthat the use of component (c) of the disclosed solid-chemicalcomposition provides an effective means of maintaining thebioavailability of the iron-containing components of the composition,which consequently provides for the long-term maintenance of highlyreducing conditions (Eh values ≦−200 millivolts) which promote theanaerobic, biologically mediated chemical-reduction processes andreactions which in turn drive the biodegradation, transformation and/ordetoxification of recalcitrant contaminants. Accordingly, theenhancement and long-term maintenance of anaerobic and reducingconditions provided for by this unique formulation of the disclosedcomposition provides for the more rapid and effective biodegradation,transformation and/or detoxification of recalcitrant organic andinorganic contaminants present in solid and liquid wastes, soils, watersor sediments.

The chemical composition of the present invention disclosed herein canbe applied to contaminated media either ex-situ or in-situ to enhancethe bioavailability and/or reactivity of recalcitrant organic andinorganic contaminants and to promote the anaerobic biodegradation,transformation, and/or detoxification of these contaminants. Inaddition, the preferred embodiments of the present invention allows forthe chemical composition disclosed herein to be combined and/orprocessed into such forms that can easily be applied to the contaminatedenvironment in-situ, eliminating the need to excavate the materials andtreat in an ex-situ manner. In the practice of the present invention,after the disclosed solid-chemical composition has been applied to thecontaminated media, the media would ideally be maintained underconditions favorable for anaerobic microbial growth, i.e., at a moisturecontent preferably close to 100% of the saturation point orwater-holding capacity of the soil or sediment, after the introductionof said chemical composition.

Another aspect of the preferred embodiment of the present invention isthe means and/or methods by which the chemical composition disclosedherein is processed into the forms of pellets, capsules or tablets,which are easier to store, handle and use than other forms of thedisclosed chemical composition. In the preferred embodiment of thepresent invention in which the chemical composition disclosed herein areprocessed into the form of pellets, capsules or tablets, it may benecessary or otherwise advantageous to use either organic or inorganicprocessing and/or binding agents in the manufacture of the pellets,capsules or tablets. In the preferred embodiment of the presentinvention, the optional processing and/or binding agents may constitutefrom 0.01% to 7% of the total composition by weight and would beselected from one or more of the group comprising additionalplant-derived materials or wastes, starch, molasses, barley maltextract, corn syrup, vegetable oils, mineral oils, surfactants,oil/water emulsions, fats or lards, animal oils, glycerine, gelatine,bentonite, montmorillonite, kaolinite, calcium carbonate, and portlandcement and any combinations thereof. In the embodiment of the presentinvention whereby such organic and/or inorganic processing agents ofcomponent (k) are used in the manufacture of pellet, capsule or tabletforms of the disclosed chemical composition, the relative amounts of theother components (a)-(j) of the disclosed composition would be adjusteddownward in a manner which retains the relative proportions of theseother components.

The preferred embodiment of the present invention in the form ofmanufactured pellets, capsules and/or tablets is similar in form tothose manufactured for the animal feed and pellet-fuel industries, suchthat this form of the present invention can be readily produced byexisting and economical means. The preferred embodiment of the presentinvention in the form of manufactured pellets, capsules and/or tabletsprovides means by which the disclosed composition is easier and safer tostore, handle, and use than other forms of both the disclosedcomposition and other means, methods and compositions for bioremediationdisclosed in the prior art. Another aspect of the preferred pellet,capsule, or tablet forms of the solid chemical composition disclosedherein is that the final specific gravity (i.e., density) of the pelletscan easily be adjusted so as to be greater than that of water, such thatthe pellets readily sink in water. In addition, the pellet, capsule, ortablet forms of the composition disclosed herein provides for thedelayed, time-release type of interaction between the composition andthe contaminated media—consequently these forms provide for theprolonged release of the various amendments incorporated into thecomposition. Hence, the pellet, capsule, or tablet forms of thedisclosed chemical composition would provide the means by which toutilize the composition in more complicated applications, such as in thebioremediation of contaminated sediments in-situ beneath natural waters(e.g., oceans, lakes, rivers, streams, and the like) and manmade waterbodies (e.g., waste-treatment lagoons and the like).

As described above, the solid chemical-composition of the presentinvention disclosed herein provides for unique advantages, means andmethods of achieving the relatively rapid and effective anaerobicbioremediation recalcitrant organic and inorganic contaminants presentin wastes, soils, waters or sediments versus the means and methodsdisclosed in the prior art. The solid-chemical composition disclosedherein and the means and methods for their intended use overcome many ofthe disadvantages associated with traditional remediation methods byproviding for the efficient and cost-effective remediation ofenvironmental contaminants on a commercial scale with minimaldisturbance to the contaminated area. The solid-chemical compositiondisclosed herein and the means and methods for their intended use alsoovercome many of the disadvantages associated with the more recentand/or advanced means and methods for the chemical and biologicalremediation of environmental contaminants disclosed in the prior art.

EXAMPLES

The following examples are provided to illustrate the technical basis,merits and unique advantages provided by the present invention withrespect to the treatment of soils contaminated with some of the mostextremely recalcitrant contaminants, including the organo-chlorinepesticides DDT and toxaphene, PCBs and PAHs. These examples are not tobe construed as limiting the present invention in any way, but aremerely presented as examples of the unique advantages and non-obviousimprovements of the present invention over the prior art and toillustrate the practice of the present invention as described in theappended claims.

EXAMPLE 1

Prior to the development of the present invention, a pilot-scale test offour different approaches to the anaerobic bioremediation of therecalcitrant, hydrophobic organochlorine pesticides DDT and toxaphenewas conducted from April 1996 though April 1997 in order to investigatethe combination of different approaches to the implementation ofdenitrification-based bioremediation and phytoremediation. One trial,initiated in February 1997 and completed in April 1997, involved the useof an embodiment of a previously disclosed “denitrification-basedbioremediation” liquid-chemical composition (Hince et al., pendingpatent application Ser. No. 08/862,782). Several claims have beenapproved at the time of this filing for the present invention disclosedherein with respect to Hince, et al. (Ser. No. 08/862,782). Among otherinventions, Hince et al. disclose several liquid-chemical compositionsfor promoting anaerobic biodegradation of toxic organic and inorganiccompounds under anaerobic conditions including denitrifying,manganese-reducing, iron-reducing, and sulfate-reducing conditions.

The pilot study trial which utilized the liquid-chemical compositionpreviously disclosed by Hince et al. (pending patent application Ser.No. 08/862,782) was the most effective method tested for thebiodegradation of the pesticides DDT and toxaphene, with significantreductions realized over the course of only three months. However, therecent reanalysis of the data from this pilot study, based in part onthe knowledge gained from more recent experiments, suggests that theplanting of the legume Lespedeza sericia in adjacent areas might havecontributed to the observed reductions. In comparison to the optimaltest plot, the plots planted with the Lespedeza sericia also realizedreductions in the pesticide concentrations, albeit over a longer period(i.e., one year). Despite the fact that upwards of 98-99% reductions ofDDT and toxaphene levels were achieved in the most successfulpilot-study test plots, the underlying mechanisms and factorsresponsible for these results were either not well understood or had notyet been identified at that time.

Subsequent to the completion of the initial pilot-scale test, microcosmstudies were conducted at a research institution without the use of thesolid-chemical composition disclosed herein in an attempt to optimizethe formulation and application of the liquid-chemical compositionspreviously disclosed by Hince et al. (pending patent application Ser.No. 08/862,782). As these microcosm studies focused on the optimizationof these previously disclosed liquid-chemical compositions, no organicor inorganic compositions, such as plant-derived materials orgeochemical amendments, were used in these experiments. These microcosmstudies were unable to reproduce the results achieved in the initialpilot study. Nonetheless, the data from these experiments led to furtherresearch concerning other means and methods of enhancing the anaerobicbiodegradation of the pesticides DDT and toxaphene.

A second pilot-scale test of four different approaches to the anaerobicbioremediation of the pesticides DDT and toxaphene was conducted fromDecember 1998 through June 1999 in order to investigate the use ofliquid-chemical compositions previously disclosed by Hince et al.(pending patent application Ser. No. 08/862,782) in combination withvarious inorganic, geochemical compositions. The second pilot-scale testwas generally not very successful in reducing organochlorine pesticideconcentrations to below the regulatory standards, which combined withthe information described in EXAMPLE 2 below, led the inventors toconduct additional experiments to investigate the effects of variousorganic and inorganic chemical compositions and combinations thereof onpesticide degradation.

EXAMPLE 2

An investigation was undertaken in the late fall of 1999 to identify thetypes of bacteria present in uncontaminated, pesticide contaminated (butuntreated) and post-treated soils associated with the pilot studiesdescribed in EXAMPLE 1. Soil samples representative of these conditionswere analyzed using denaturing gradient gel electrophoresis (DGGE)methods to separate and sequence the 16S rDNA genes of the bacteriapresent. The results of the DGGE 16S rDNA analyses were compared to aninternational computer database for bacterial DNA. The resultant DGGE“gels” revealed that novel Fibrobacter spp. dominated the microbialcommunity present in the post-treated sample, whereas such species weresignificantly less abundant in the DGGE gels for thecontaminated-but-untreated sample and the “clean” sample. The resultsalso indicated that other novel and/or previously unexpected “adapted”populations of soil and/or legume-related bacteria such as Rhizobiumspp. and Bradyrhizobium spp., as well as soil bacteria such asPseudomonas spp. and Geobacter spp., were evident in the bacterialcommunities identified in the samples from the contaminated and/orsuccessfully treated locations.

Subsequent investigation of the scientific literature and relatedresearch conducted from December 1998 to date has indicated thatFibrobacter spp. are known to be plant-fiber degrading (e.g., lignin andcellulose-degrading) bacteria for which the “conventional wisdom” andprior art have held are most commonly associated with the breakdown ofplant fiber in the rumen of cattle and similar environments.Furthermore, the available literature indicate that Fibrobacter spp. areanaerobic bacteria. In addition, the subsequent research has indicatedthat the Rhizobium spp. and Bradyrhizobium spp. are legume-relatedbacteria associated with the roots of legumes which are responsible forthe anaerobic fixation of elemental nitrogen. Moreover, Bradyrhizobiumspp. were found to be the specific bacterial symbionts found inassociation with the roots of Lespedeza spp. Hence, these results led tothe novel hypothesis disclosed herein that such fiber-degradingbacteria, (and possibly the legume-related bacteria as well), wereeither directly responsible for the biodegradation of the pesticidesand/or carried out processes which greatly increased the bioavailabilityof the pesticides to other anaerobic, contaminant-degradingmicroorganisms.

EXAMPLE 3

Subsequent to the experiments described above, several additional setsof bench-scale, microcosm experiments were conducted in the laboratoryto investigate the effectiveness of different embodiments of the organicsolid-chemical composition disclosed herein alone and in combinationwith a consistent embodiment of the inorganic solid-chemical compositiondisclosed herein on pesticide degradation. In addition, both apreviously disclosed liquid-chemical composition (Hince et al., pendingpatent application Ser. No. 08/862,782) and a novel liquid-chemicalcomposition were used in these experiments. As shown in FIG. 1,experimental cohorts S-10 and S-11 exhibited negative Eh valuesimmediately after treatment followed by a rapid decline in Eh valueswhich stabilized within the range of −300 to −400 millivoltsapproximately one month after treatment. The most successful cohorts,S-10 and S-11, were treated with the chemical composition disclosedherein comprised of a simplified organic embodiment of composition,i.e., alfalfa meal only, and an inorganic embodiment of compositionwhich included the following components: (i) Ancor Image 100 “spongeiron,” a highly porous form of fine granular iron manufactured by theHoeganaes Corporation, (ii) pyrolusite (i.e., manganese dioxide), and(iii) “yellow boy” (i.e., a biogenic ferric oxyhydroxide obtained froman acid-mine drainage site in Pennsylvania) within the specifiedconcentration ranges and proportions of the present invention asdisclosed herein.

The observed trends in pesticide degradation were found to closelyfollow the observed trends of low-Eh conditions (and the stabilizationthereof). As shown in FIGS. 2 and 3, cohorts S-7 and S-8, which wereonly treated with an embodiment of the inorganic solid-chemicalcomposition disclosed herein and/or a liquid-chemical compositionpreviously disclosed by Hince et al. (pending patent application Ser.No. 08/862,782) demonstrated half-lives on the order of a minimum ofthree months. Cohorts S-10X, S-11X and S-12X, which were only treatedwith an embodiment of the primarily organic solid-chemical compositiondisclosed herein and a previously disclosed liquid-chemical composition(Hince et al., pending patent application Ser. No. 08/862,782) achievedbetter treatment half-times which ranged from 17-to-99 days for DDT and28-to-36 days for toxaphene. Cohorts S-10, S-11 and S-12, which weretreated with the aforementioned, simplified embodiment of thesolid-chemical composition disclosed herein and either novel and/orpreviously disclosed liquid-chemical compositions, achieved betterresults (overall) with treatment half-times ranging from 2781 days forDDT and 2535 days for toxaphene.

The best overall pesticide-biodegradation results were achieved withtreatment Cohort 13, which yielded treatment half-times of 13 days forboth DDT and toxaphene. Cohort 13 was treated with an improvedembodiment of the chemical composition which included the aforementionedinorganic components of composition and an organic embodiment of thecomposition which included both (i) alfalfa meal and (ii) a cotton lintmaterial.

These data indicate that each of the organic and inorganic components ofthe chemical composition disclosed herein and used in these experimentseffectively promoted the biodegradation of the pesticides. Theplant-derived components of the disclosed composition appear to promotethe physical and/or biogeochemically mediated solid-phase extraction ofthe hydrophobic pesticides. The geochemical components of the chemicalcomposition appear to help increase the biogeochemical reactivity of thepesticides, and help to establish and maintain low-Eh conditions, whichin turn promote various biogeochemical reactions and processes mediatedby anaerobic microorganisms. The data also indicate that the geochemicalembodiment of the composition tested provided the specific advantage ofhelping to create and maintain stable low-Eh conditions for extendedtime periods which enhances the speed and effectiveness of contaminantbiodegradation. The data from these experiments support the conclusionthat the preferred embodiment of the present invention represented byexperimental cohort S-13, provided the most rapid and effective meansfor promoting the anaerobic biodegradation, transformation and/ordetoxification of DDT and toxaphene.

EXAMPLE 4

A pilot-scale test was recently initiated which involved the applicationof the chemical composition disclosed herein to PCB and PAH-contaminatedsludge materials at an industrial site. This sludge material posed theadditional challenge in that its solid matrix is primarily comprised ofgypsum (i.e., calcium sulfate). Several previous studies have indicatedthat the presence of sulfates tends to inhibit the microbial degradationof PCBs, PAHs and other recalcitrant contaminants. Nonetheless, the mostrecent data available from this ongoing experiment has indicated thatthe levels of PCB aroclors and heavy hydrocarbons in the sludge werereduced by nearly 40% and 55% percent, respectively, 27 days aftertreatment with the present invention. Other observations, such as apreferential loss of low-molecular weight PCB congeners and shifts inthe congener profiles towards less-chlorinated congeners, providesadditional evidence that the chemical composition used in this study anddisclosed herein is able to effectively and rapidly reduce PCB and PAHlevels in the gypsum sludge despite the presence of extremely highlevels of sulfate.

The invention has been described with reference to particularembodiments. However, it should be obvious to those skilled in the artto which this invention pertains that other modifications andenhancements can be made without departing from the scope of the claimsthat follow.

We claim:
 1. A solid-chemical composition, comprising: a. one or moreplant materials selected from the group consisting of the plant familiesLeguminosae and Phaeophyte from about 10% to 95%, by weight percent, ofsaid composition; b. a source of iron, being a reducing agent and amicrobial electron acceptor for anaerobic respiration, selected from thegroup consisting of metallic iron particles and steel particles andcombinations thereof from about 1% to 50%, by weight percent of saidcomposition; c. a source of Mn(IV), being an oxidative catalyst and amicrobial electron acceptor for anaerobic respiration, selected from thegroup consisting of metallic manganese particles and particles ofmanganese (IV) minerals and combinations thereof from about 0.01% to37.5%, by weight percent. of said composition.
 2. A solid-chemicalcomposition in accordance with claim 1, whereby said chemicalcomposition has the capacity to extract and absorb hydrophobic chemicalcontaminants and to create and maintain anaerobic and reducingconditions so as to promote the anaerobic bioremediation and chemicalreduction of said contaminants in environmental media.
 3. A chemicalcomposition in accordance with claim 1, further comprising one or morenitrate salts, said nitrate being a microbial electron acceptor andnutrient form of nitrogen, selected from the group consisting of sodiumnitrate, sodium-potassium nitrate, and potassium nitrate from about 0.5%to 4%, by weight percent, of said composition.
 4. A chemical compositionin accordance with claim 1, further comprising one or more complexphosphates selected from the group consisting of sodiumhexametaphosphate, sodium trimetaphosphate and other biologicallyhydrolyzable ringed metaphosphates and linear polyphosphates from about0.02% to 20%, by weight percent, of said composition.
 5. A chemicalcomposition in accordance with claim 1, further comprising a chelatingagent selected from the group consisting of citric acid, humic acid,fulvic acid, sodium citrate, nitrilotriacetic acid (NTA),ethylenediaminetetraacetic acid (EDTA) and combinations thereof fromabout 0.01% to 5%, by weight percent, of said composition.
 6. A chemicalcomposition in accordance with claim 1, further comprising one or morebiogeochemically produced minerals selected from the group consisting ofiron oxides, iron hydroxides, and iron oxyhydroxides from about 0.001%to 15%, by weight percent, of said composition.
 7. A chemicalcomposition in accordance with claim 1, further comprising yellow boy,being a form of iron oxyhydroxides produced by microorganisms frommine-drainage wastes and the treatment thereof from about 0.01% to 15%,by weight percent, of said composition.
 8. A chemical composition inaccordance with claim 1, wherein said source of iron comprises spongeiron particles, being a porous form of iron particles.
 9. A chemicalcomposition in accordance with claim 1, wherein said source of Mn(IV) isselected from the group consisting of pyrolusite, psilomelane, manganesegreensand, other minerals containing Mn(IV) and combinations thereof.10. A chemical composition in accordance with claim 1, furthercomprising a microbial inoculum, said microbial inoculum being a sourceof microorganisms from about 0.001% to 1%, by weight percent, of saidcomposition.
 11. A chemical composition in accordance with claim 1,further comprising a microbial inoculum, said microbial inoculum being asource of microorganisms. wherein said microorganisms are selected fromthe group consisting of soil bacteria, metal-reducing bacteria,legume-related bacteria, plant-fiber degrading bacteria, plant-fiberdegrading fungi and combinations thereof from about 0.001% to 1%, byweight percent, of said composition.
 12. A chemical composition inaccordance with claim 1, further comprising a microbial inoculum, saidmicrobial inoculum being a source of microorganisms, wherein saidmicroorganisms are selected from the group consisting of Rhizobium spp.,Bradyrhizobium spp., Fibrobacter spp., Clostridium spp., Pseudomonasspp., Geobacter spp. and combinations thereof from about 0.001% to 1%,by weight percent, of said composition.
 13. A chemical composition inaccordance with claim 1, wherein said plant materials of the plantfamily Leguminosae are further selected from the group consisting ofplant species from the genera Lespedeza, Medicago, Vicia, Glycine,Lathyrus, Trifolium and combinations thereof.
 14. A chemical compositionin accordance with claim 1, wherein said plant materials of the plantfamily Leguininosae comprise alfalfa.
 15. A chemical composition inaccordance with claim 1, wherein said plant materials of the plantfamily Phaeophyta are further selected from the marine plant genusSargassum.
 16. A chemical composition in accordance with claim 1,further comprising plant materials selected from the group consisting ofthe plant families Gossypium and Cannabacea and combinations thereoffrom about 1% to 89%, by weight percent, of said composition.
 17. Achemical composition in accordance with claim 1, further comprisingplant materials from the plant family Gossypium, wherein said plantmaterials are further selected from the group consisting of cotton lintand other fibrous cotton-containing materials and wastes produced by thecultivation and processing of cotton, cotton plants, and cotton seedfrom about 1% to 89%, by weight percent, of said composition.
 18. Achemical composition in accordance with claim 1, further comprisingplant materials selected from the plant family Cannabacea, wherein saidplant materials are further selected from the group consisting offibrous plant materials and wastes produced by the cultivation andprocessing of hemp plants, hops plants and combinations thereof fromabout 1% to 89%, by weight percent, of said composition.
 19. A chemicalcomposition in accordance with claim 1, further comprising plantmaterials selected from the group consisting of the plant familiesTriticum, Aegilops and combinations thereof from about 0.5% to 30%, byweight percent, of said composition.
 20. A chemical composition inaccordance with claim 1, further comprising plant materials selectedfrom the group consisting of the plant families Triticum and Aegilops,wherein said plant materials are further selected from the groupconsisting of fibrous plant materials and wastes produced by thecultivation or processing of wheat, oats, barley, and rye from about0.5% to 30%, by weight percent, of said composition.
 21. A chemicalcomposition in accordance with claims 1, 13, 14, 15, 16, 17, 18, 19 or20, wherein said plant materials are in a form selected from the groupconsisting of powders, flour, pellets, tablets, capsules, meals, mids,husks, hulls, hays, straws and combinations thereof.
 22. A chemicalcomposition in accordance with claims 1, 13, 14, 15, 16, 17, 18, 19 or20 wherein any said plant materials are in dehydrated, dried orfreeze-dried forms.
 23. A chemical composition in accordance with claim1, wherein said materials comprising said composition are in the form offinely divided particles and wherein said particles have a medianparticle diameter in the range defined as being from less than or equalto clay-sized particles (≦2 μm) to less than or equal to medium-sandsized particles (0.5 mm).
 24. A chemical composition in accordance withclaim 1, wherein the proportion of said source of manganese (IV) to saidsource of iron, by weight, is in the range of from about 0.01 to 0.75.25. A chemical composition in accordance with claims 1, 13, 14, 15, 16,17, 18, 19 or 20, wherein the carbon to nitrogen ratio of the totalamount of any said plant materials in any said embodiment of saidcomposition, by weight, is in the range of from about 15 to 1 to about45 to
 1. 26. A chemical composition in accordance with claim 1, furthercomprising a binding agent selected from the group consisting ofplant-derived materials, starch, molasses barley malt extract, cornsyrup, glycerin, gelatine, bentonite, montmorillonite, kaolinite,calcium carbonate, portland cement and combinations thereof from about0.1% to 7%, by weight percent, of said composition.
 27. A chemicalcomposition in accordance with claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,12, 13, 14, 15, 16, 17, 18, 19, 20, 23, 24, or 26 wherein saidembodiment of said composition is prepared in one or more forms selectedfrom the group consisting of briquettes, granules, pellets, tablets, andcapsules.
 28. A method for environmental remediation in accordance withthe chemical composition of claims 1, 13, 15, 16, 17, 18, 19 or 20whereby said plant materials of said embodiment of said composition,excepting those of the plant family Phaeophyta, are cultivated in-situwithin the contaminated media by means of planting and growing saidplants.
 29. A method in accordance with claim 28, wherein said plantmaterials that are cultivated in-situ are subsequently overwinteredin-situ via their exposure to one or more periods of freezingtemperatures.
 30. A method for the anaerobic bioremediation and chemicalreduction of chemical contaminants in contaminated media, saidcontaminated media being one or more of the group consisting ofindustrial wastes, solid wastes, hazardous wastes, sludges, liquidwastes, soils, sediments, aqueous sediments, ground waters, and surfacewaters, comprising the application of said embodiment of saidsolid-chemical composition of claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,12, 13, 14, 15, 16, 17, 18, 19, 20, 23, 24, or 26 at a rate from about0.05 to 500 grams of said composition per Kg of said contaminated media,by weight.
 31. A method for the remediation of contaminated groundwater, comprising the application of said embodiment of saidsolid-chemical composition of claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,12, 13, 14, 15, 16, 17, 18, 19, 20, 23, 24, or 26 within asemi-permeable reactive barrier.
 32. A Method for environmentalremediation whereby the application of said embodiment of saidsolid-chemical composition of claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,12, 13, 14, 15, 16, 17, 18, 19, 20, 23, 24, or 26 to contaminated wastesor environmental media is supplemented with a liquid-chemicalcomposition comprising a mixture of water with one or more materialsselected from the group consisting of nitrates, nitrites, nitrousoxides, phosphates, surfactants, alcohols, vegetable oils, mineral oils,sugars, starches, corn syrup, barley malt extract, molasses, humicacids, fulvic acids, chelating agents, and acidifying agents.